Endocrine Abstracts

Fine-needle aspiration (FNA) is the best available technique for preoperative diagnosis of malignancy in thyroid nodules. Although its efficiency has been well described, the learning curve is underreported. We aimed to describe the learning curve of a new FNA facility (endocrinologist/pathologist) in a university based hospital.

Methods: In February 2018 a new FNA facility was formed in our hospital comprising an endocrinologist with high experience in thyroid ultrasound but without any experience in FNA and a pathologist with occasional activity in thyroid FNA. We assessed all FNA procedures of thyroid nodules until December 2019 (791 nodules). The nodules were chronologically grouped in 4 groups of 200 nodules (191 in the last group).

Results: The number of slides per nodule decreased from 5 ± 1.6 in the first group to 4.9 ± 1.4, 4.3 ± 1.0 and 4.1 ± 1.1 in the second, third and fourth group respectively (ANOVA P < 0.001) while the nodule greatest dimension remained constant (around 26 mm). The percent of Bethesda 1, 3 and 4 decreased from 14.5%, 12.5% and 31.5% in the first group to 10.5%, 10% and 18.5% in the second, 5%, 5.5% and 9.5% in the third and 10.5%, 3.7% and 10.5% in the last group. In surgically treated nodules the risk of malignancy 100%, 100%, 92.3% and 100% respectively for Bethesda 5/6 and 30.6%, 36.3%, 22.2% and 60% respectively for Bethesda 4 categories.

Conclusion: The efficiency parameters of a new thyroid FNA facility continue to improve at least until 800 procedures. However, most parameters are within the literature reported range after 200–400 procedures.